From the battery specs the NiMh Botvac systems are 12v nominal batteries, while the lithium equipped Connected series uses 15v the same as the XV twin pack NIMh -- as the higher lithium cell voltage 3.6v divides more closely to that higher level, using a four series. Four series lithium replacements can be used in XV's. So for charging, the NiMh Botvac docks are 18v and the higher voltage XV and Connected docks are 22-24v. I do not think an NiMh Botvac 18v dock could be used for charging a Connected Botvac at least reliably. Dock voltages are stepped down, with a constant current buck voltage converter (switching power supply), for charging so there can be some charging with a lower voltage dock. The dock voltage is higher than the battery voltage for losses in the step down conversion, and to supply a little higher voltage than the battery to push charge into the cells.

Applying a 24v dock supply to the Botvac NiMh charger expecting 18v could potentially blow some component not specified for that higher voltage -- unknown. At least an old XV board was found vulnerable when the charger got accidentally set up in tinkering to apply over 21v to the board -- some under specified component damaged in the charging and battery management circuit. (The 15v NiMh system normally peaks out in charging near 18.5v on the battery terminals when full.) The four series lithium batteries terminate charging at 16.8v the maximum allowed on the lithium cells, where charging is controlled by voltage. The NiMh charging is terminated by temperature rise in the pack, as NiMh when full converts continuing current into heat.

Let me explain what I was doing.I have a D85 but that charger is broken! I also have a new Connected D3 with of course a working charger.That working charger has exactly the same output voltage. Both Neato's are stated 18VDC. So I expected that the older D85 can be charged with the new dock,... wrong!

Sometimes you see the charging light is pulsating but it is not charging the battery!

I tested this theory with the new D3 and supplied 18VDC with a stable power supply. On the D3 it looked like it was charging because the green battery sign started pulsating. But when I looked at the status in the app, it was not doing anything. When you place the D3 on the dock besides the charging sign on the bot it also has a sign in the app.

Conclusion: You cannot use a dock ment for the D3 to charge the D85 although the voltage is the same!

When the circuits inside the XV docks were examined here by an engineer some time ago, a change was noticed where an inductor appeared moved from inside the bot into the dock. There was a change in the dock power bricks (separate on XV's, and also integrated into the dock on Botvac). It is possible the buck voltage converter for the charger had parts split between the dock and the bot system board. The design of the charging system could vary between the different Neato models. An incompatibility was announced, where the old docks would not charge the newer model bots in the XV line, while new docks could still charge the old bots, backwards compatible. A complex power management IC could also be seen in the dock circuits, functions not known. There is a safety system to turn on full charging current only when the bot is connected, and this has changed from a resistor across the bot charging contacts which loads the dock, to something else more sophisticated. That resistor ran hot and could contribute to a problem of heat they had melting rear plastic. It appears there are different types of docks and charging circuits which must be matched to the vacuum model. A complete analysis of the dock circuits has not been made.

Charging operation can be observed over USB with the Neato Control program or terminal emulator, showing the charging current and voltage, and fuel guage per cent. The bot panel light is only partly indicative of what is happening (the NiMh charging is especially convoluted with low current "topping off" phases after the indicator shows full, for the heating and cooling involved with NiMh).

I had a Botvac connected using Li-Ion battery. The charger parts # is 905-0310 rated output is 18VDC 36W 2.0A. Measured no load voutage is 18.9V

After reading this thread, I am going over the charging dock with the Botvac in my shop.- Botvac D85 using NiMH battery with the same charger as the Botvac 905-0310. Measured no load output is 19.0V- Botvac 65 using NiMH battery. Charger parts# 905-0095, output is 18VDC 36W 2.0A. Measured no load voutage is 19.4V

I was surprised that both NiMH and LI-Ion chargers have the same output voltage.

I am not sure that whether my client mixed up the Botvac D85 charger with a Botvac connected charger.

No surprise because the dock is a power supply for a variable voltage, constant current charging circuit on the main board (typically 2 amps on Neato). The dock supply will be higher than the battery terminal voltage (increasing as batteries fill), for the losses in the constant current regulator (either linear component or a buck voltage converter circuit with an inductor).The NiMh charger will output higher voltages than the Lithium algorithm (difference set in software) for pushing charge into NiMh, while lithium charging stops at a maximum voltage (NiMh based on heating in the pack, using thermistor input). Open single cell NiMh chargers stop on a small drop in voltage when full, but the enclosed packs need to avoid over heating; when near full NiMh converts charging current into dissipated heat; lithium remains cool.

Also consider that the NiMh Botvac is a 12v system while I think the newer lithium, connected models run on the same 15v as the old XV because the higher voltage of lithium cells compared to 1.2v NiMh does not divide well into 12v. The NiMh Botvac charger is 18v but the lithium models might be higher similar to XV's, would have to check.